on waitFor pMS
put the millisec into tMS
put the millisec - tMS into tMSDiff
repeat until tMSDiff >= pMS
put the millisec - tMS into tMSDiff
end repeat
end waitFor

Obviously, this causes the stack to hang and can't process any messages. One handy thing though is that buttons and other UI items also become unresponsive, so it prevents user interaction during this time (without affecting the rest of the browser).

I'm working on a way to do it with messages. I'll post here when I'm done.

on myCommand_1
-- Do some stuff...
send "myCommand_2 tMyParametersToPassInAnArray" to me in 1 second
-- ^ Is the same as 'wait 1 sec with messages' ^
end myCommand_1
on myCommand_2 pParameterArrayPassedFromPreviousHandler
-- Break out the parameters if you don't want to carry on using them in the array...
-- Carry on and do more stuff...
end myCommand_2